The granule morphology, microstructure, and thermal properties of micronized cassava starch prepared by a vacuum ball-grinding machine were investigated. Scanning electron microscopy (SEM) analysis indicated that the morphology of starch granule changes during the ball-grinding treatment. Differential scanning calorimetry (DSC) analysis indicated that the maximum peak temperature (T-p) of the gelatinization process, the glass transition (T-g), and peak height index (PHI) for the starch granules decreased when the size of micronized starch granules was reduced. When the size of starch granules was reduced beyond 9.11 mu m, they have a tendency to agglomerate and their Delta H were increased. The granule size has a significant effect on the gelatinization properties of cassava starch. This study will provide useful information of the micronized starch for its potential industrial application. (C) 2009 Elsevier Ltd. All rights reserved.